The prior art refers to a command procedure for a magnetic bearing of the type mentioned above. During such a process, an actuator directs the rotation of the rotor around its axis of rotation, this rotation corresponding to a given degree of freedom for the rotor. Excitation of the five other degrees of freedom of the rotor is an undesirable disruption that must be corrected by the means of command. To do this, the means of command, in standard form, comprise one command unit for each degree of freedom of the rotor, the command of each degree of freedom of the rotor thus being separated from the commands for the other degrees of freedom. However, for high rotor-rotation speeds, such command procedures have proved unsuitable. In fact, because of the precession movements caused by the gyroscopic effect of the rotor, coupling occurs between the degrees of freedom. For these rotation speeds, the correction of the movements of the rotor by means of these standard command procedures is therefore relatively unstable. In addition, the performance of the electric motor associated with the rotor is noticeably reduced.
To overcome this problem, document EP 1,771,667 B1 describes a command procedure for a magnetic bearing, within which the methods of precession of the rotor, combined with the precession movements, are taken into account by the means of command. More specifically, different correctors are modelled, each corrector taking account of the modes of precession of the rotor in the form of outside uncertainties. The command procedure therefore involves, for a given speed of rotation of the rotor, selection of the most suitable corrector. In such a procedure, correction of the precession movements of the rotor may prove selectively stable, especially in close proximity to the speeds of rotation for which the correctors have been designed. However, such a command procedure does not guarantee stability of correction throughout the full range of speeds of rotation of the rotor, especially when passing from one corrector to another. In addition, as the rotor precession modes are based on outside uncertainties, these uncertainties also constitute sources of instability for final the correction.